a)-7x+8x-12=x-12
b) 3a-8a +10=10-5a=5(2-a)
c)12xy+3xy-19xy=-4xy
d)11x²-5 x²+23 x²=29x²
e)2 / 3 x² +1 /2 x²-x²=4x²/6+3x²/6-6x²/6=x²/6
f)-1/3 x+5 /6 x+2x-7/2 x=-2x/6+5x/6+12x/6-21x/6=-6x/6=-x
g)0,(3) a²b-4/3a²b-5/6a²b=3/9a²b-4/3a²b-5/9a²b=1/3a²b-4/3a²b-5/6a²b=-a²b-5/6a²b=-11a²b/6
h)2√2xyz-√8xyz+√18xyz=xyz(2√2-2√2+3√2)=3√2xyz
i)1/6ax²-0,75ax²-0,5ax²+ax²=ax²(1/6-0,75-0,5+1)=-0,08(3)ax²
j)1/2xy+2/4xy-5/4xy=xy(1/2+2/4+5/4)=xy(1+5/4)=xy(4/4+5/4)=9/4xy
